An updated version of Firefox is available to address the issues with Add-ons disabled or fail to install on Firefox. You can download the update for your OS here: https://www.mozilla.org/firefox/new/
For Known Issues and Workarounds, please check out the update at https://support.mozilla.org/kb/add-ons-disabled-or-fail-to-install-firefox

Import Bookmarks from Internet Explorer or Microsoft Edge

Firefox lets you import your Favorites (called Bookmarks in Firefox), settings and other data from Microsoft Edge or Internet Explorer, saving you from having to configure many things yourself. This article gives you step-by-step instructions for getting it done.